Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We previously identified a major enhancer of the mouse ferritin H gene (FER-1) that is central to repression of the ferritin H gene by the adenovirus E1A oncogene (Tsuji, Y., Akebi, N., Lam, T. K., Nakabeppu, Y., Torti, S. V., and Torti, F. M. (1995) Mol. Cell. Biol. 15, 5152-5164). To dissect the molecular mechanism of transcriptional regulation of ferritin H, E1A mutants were tested for their ability to repress FER-1 enhancer activity using cotransfection with ferritin H-chloramphenicol acetyltransferase (CAT) reporter constructs. Here we report that p300/CBP transcriptional adaptor proteins are involved in the regulation of ferritin H transcription through the FER-1 enhancer element. Thus, E1A mutants that failed to bind p300/CBP lost the ability to repress FER-1, whereas mutants of E1A that abrogated its interaction with Rb, p107, or p130 were fully functional in transcriptional repression. Transfection with E1A did not affect endogenous p300/CBP levels, suggesting that repression of FER-1 by E1A is not due to repression of p300/CBP synthesis, but to E1A and p300/CBP interaction. In addition, we have demonstrated that transfection of a p300 expression plasmid significantly activated ferritin H-CAT containing the FER-1 enhancer, but had a marginal effect on ferritin H-CAT with FER-1 deleted. Furthermore, both wild-type p300 and a p300 mutant that failed to bind E1A but retained an adaptor function restored FER-1 enhancer activity repressed by E1A. Sodium butyrate, an inhibitor of histone deacetylase, mimicked p300/CBP function in activation of ferritin H-CAT and elevation of endogenous ferritin H mRNA, suggesting that the histone acetyltransferase activity of p300/CBP or its associated proteins may contribute to the activation of ferritin H transcription. Recruitment of these broadly active transcriptional adaptor proteins for ferritin H synthesis may represent an important mechanism by which changes in iron metabolism are coordinated with other cellular responses mediated by p300/CBP.
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PMID:Transcriptional regulation of the mouse ferritin H gene. Involvement of p300/CBP adaptor proteins in FER-1 enhancer activity. 1006 17

Lipofection, a lipid-mediated DNA transfection procedure, was used to transfect synchronized L929 mouse fibroblast cells with a reporter plasmid containing the bacterial chloramphenicol acetyltransferase gene. The efficiency of gene expression was investigated on transfection of cells at different stages of the cell cycle. Our data show that expression of the reporter gene was minimal when transfection was performed in G0-phase and parallel experimental data disproved the possibility that the reduced expression observed was due to differential uptake at different times in the cell cycle. Investigation into the condensation state of the plasmid has shown that the low chloramphenicol acetyltransferase gene expression could be a direct consequence of the packaging of the plasmid into condensed chromatin when transfection occurs in G0-phase. The inactivation of the reporter gene is not reversed by growth of the cells in high serum or by treatment with Trichostatin A, a specific inhibitor of histone deacetylase, suggesting that the inactive chromatin formed in G0-phase cells lacks associated histone acetylase activity. In contrast, the high activity seen when cells in S-phase are transfected is enhanced even further by treatment with Trichostatin A.
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PMID:Efficiency of expression of transfected genes depends on the cell cycle. 1063 9

To compare the role of histone deactylation in estrogen activation of a transiently transfected vitellogenin (VIT) promoter and an integrated VIT promoter in the same cells, we produced three HepG2, human hepatoma, cell lines (HepG2ERV cells) stably expressing human estrogen receptor alpha (hERalpha) and containing an integrated VIT promoter-chloramphenicol acetyltransferase (VIT-CAT) reporter gene. The three ER-positive HepG2ERV cell lines and wild-type, ER-negative, HepG2 cells cotransfected with cytomegalovirus-hERalpha exhibited similar MOX-dependent inductions of 20- to 50-fold with a transiently transfected VIT-luciferase reporter and 15- to 50-fold with a transfected 4-estrogen response element-TATA-luciferase reporter gene. The histone deacetylase inhibitor, trichostatin A, did not enhance MOX induction of the transiently transfected VIT promoter in the HepG2ERV cells. In contrast, trichostatin A dramatically potentiated MOX induction of the stably integrated VIT-CAT reporter gene, resulting in MOX-ER-dependent increases in CAT activity of up to 600-fold. These data demonstrate that although liganded ER exhibits the capacity to fully activate a transiently transfected VIT promoter, under some circumstances the ability to reorganize a repressive chromatin structure may be limiting for steroid receptor action.
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PMID:A histone deacetylase inhibitor potentiates estrogen receptor activation of a stably integrated vitellogenin promoter in HepG2 cells. 1087 35

The human progesterone receptor (PR) contains multiple Ser-Pro phosphorylation sites that are potential substrates for cyclin-dependent kinases, suggesting that PR activity might be regulated during the cell cycle. Using T47D breast cancer cells stably transfected with an mouse mammary tumor virus (MMTV) chloramphenicol acetyltransferase reporter (Cat0) synchronized in different phases of the cell cycle, we found that PR function and phosphorylation is remarkably cell cycle dependent, with the highest activity in S phase. Although PR expression was reduced in the G2/M phase, the activity per molecule of receptor was markedly reduced in both G1 and G2/M phases compared to the results seen with the S phase of the cell cycle. Although PR is recruited to the MMTV promoter equivalently in the G1 and S phases, recruitment of SRC-1, SRC-3, and, consequently, CBP is reduced in G1 phase despite comparable expression levels of SRC-1 and SRC-3. In G2/M phase, site-specific phosphorylation of PR at Ser162 and at Ser294, a site previously reported to be critical for transcriptional activity and receptor turnover, was abolished. Treatment with the histone deacetylase inhibitor trichostatin A elevated G1 and G2/M activity to that of the S phase, indicating that the failure to recruit sufficient levels of active histone acetyltransferase is the primary defect in PR-mediated transactivation.
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PMID:Human progesterone receptor displays cell cycle-dependent changes in transcriptional activity. 1579 79